Canadian researchers examined data on all 129 cycling deaths that occurred in the province of Ontario between January 2006 and December 2010. The cyclists ranged in age from 10 to 83 years old, and 86 percent were boys or men. Motor vehicles were involved in 77 percent of the deaths.

Cyclists who died of a head injury were three times less likely to be wearing a helmet than those who died of other injuries, according to the study, which was published in the CMAJ (Canadian Medical Association Journal).

"We saw an association between dying as a result of sustaining head injury and not wearing a helmet," wrote Dr. Navindra Persaud, of the Keenan Research Centre and the Department of Family and Community Medicine at St. Michael's Hospital in Toronto, and co-authors. "These results are consistent with a protective effect of helmets on cycling deaths."

The findings mean that cyclists who do not wear a helmet have a three times greater risk of dying from head injuries than those who wear a helmet.

Cycling deaths account for more than 2 percent of traffic fatalities, according to a journal news release. One cyclist dies every week in Canada.

"While legislating helmet use is controversial and inconsistent in Canada, our study shows that wearing helmets saves lives," Persaud and colleagues said. "Policies and campaigns that promote helmet use may decrease cycling mortality."

More information

The U.S. National Highway Traffic Safety Administration has more about bicycle safety.